Structural components installed inside liquid containers have a tendency to generate high resonance vibrations caused by movement of the tank, even if the tank is completely filled with liquid so that there is substantially no movement of liquid independently of any tank movement. Such response vibrations are triggered by input vibrations even if the tank is full of liquid. Such resonant vibrations are believed to be due to the rather small dynamic damping of these installed components in the tanks or rather of the vibrations of these components. As a result of these vibrations the components are exposed to substantial fatigue stress which can readily cause a fracture and thus lead to the failure of the particular structural component and even to failure of an entire mission.
The above mentioned vibrations have nothing to do with the problem of the so-called "sloshing effect" that occurs in liquid tanks that are not full and are moving. The sloshing effect occurs, for example, in fuel tanks in a moving vehicle. Various anti-sloshing devices are known for the purpose of retarding or calming the movement of a liquid in a tank. These devices are positioned inside the tank and are connected to the tank wall, see for example U.S. Pat. No. 4,844,278 (Freiwald et al.), issued Jul. 4, 1989, and U.S. Pat. No. 5,031,795 (Kotera et al.), issued Jul. 16, 1991.
It is also known to suppress oscillations or so-called "strumming" of structures immersed in a fluid flow, such as a smokestack exposed to wind flow, a periscope exposed to water flow, etc. The oscillation suppressing devices are attached to the outside surfaces of the structure for influencing the fluid flow pattern. See, for example, U.S. Pat. No. 3,804,210 (Erickson), issued on Apr. 16, 1974 or U.S. Pat. No. 3,884,173 (Fabula), issued on May 20, 1975.